Nucleic acid binding proteins are of major importance in biology since they include many of the factors that regulate gene expression and developmental processes. One major class of such factors are constituted by the family of zinc finger proteins, defined by conserved structural motifs which require zinc ions for appropriate folding into active forms. The aim of this project has been the genetic and molecular analysis of human genes encoding zinc finger proteins. A major focus of study has been an analysis of the number of zinc finger proteins that are encoded in the human genome, and the issue of how these genes are distributed on the chromosomes. These questions have been addressed specifically with regard to the C2H2 family of zinc finger proteins in the following way. Over 200 genomic clones have been isolated; of these, over 90 clones have been sorted into 25 genes by crosshybridization, partial sequencing, and PCR amplification. Further, these loci have been mapped onto the human chromosome complement by nonradioactive in situ hybridization techniques. The results show that zinc finger genes are distributed on many chromosomes but are especially abundant on chromosome 19. By extrapolation to additional clones obtained in this and in other laboratories it can be estimated that the human genome contains at least one hundred, and probably several hundred, genes for zinc finger proteins of the C2H2 class. These results illustrate the high complexity of the regulatory hierarchies that involve nucleic acid binding proteins in the regulation of gene activity.